Influence of treatment against decomposition and water absorption on fiber matrix interfacial shear strength of glass fiber reinforced PLA

Glass Fiber Reinforced Plastics (GFRP) have been used for various applications such as automobiles, motorboats and so on. Since GFRP in which thermosetting resins are used as a matrix is difficult to recycle, thermoplastic resins superior in recyclability have been receiving attention. Especially, polylactic acid (PLA), which is plant-derived and biodegradable resin, has been receiving attention as an environmentally friendly material. When PLA is used as a matrix of FRP, it is necessary to suppress hydrolysis at the time of use as in ordinary petroleum-based plastics. Recently, a method to decrease the rate of decomposition of PLA has been developed by combining a decomposition inhibitor (Poly Methyl Methacrylate: PMMA) with PLA and annealing treatment. For a decomposition inhibitor PMMA, in which the methyl ester group protects the ester group of PLA, suppress the hydrolysis during use. By performing an annealing treatment, the degree of crystallization of PLA is increased and the progress of hydrolysis can be delayed. As described above, although PLA with higher resistance to hydrolysis have been developed, the mechanical properties of GFRP using PLA decomposition inhibitor as a matrix have not been clarified yet. In this study, single fiber pull-out tests were conducted by using GF/PLA model composites to clarify the influence of decomposition inhibitor and annealing treatment. Though the fiber/matrix interfacial shear strength was decreased by water absorption, the decomposition rate for GF/PLA with a decomposition inhibitor and annealing treatment was the lowest and showed excellent water resistance. © 2018 The Society of Materials Science, Japan.